Project 1). Optokinetic and vestibular nystagmus interplay. We have found that some patients with cerebellar degeneration have a poor response. Most cerebellar patients have an increased or uninhibited caloric response. These two factors tend to make post-caloric nystagmus dominant to an induced OKN response in cerebellar lesions. In normal patients OKN is dominant to a post-caloric response. We wish to verify this hypothesis by examining patients with cerebellar degeneration and comparing them with controls. Project 2). Hyperventilation can cause disorientation in some patients. We wish to study the effects of hyperventilation in various positions and positioning procedures available to us. Project 3) We have numerous patients who have undergone a labyrinthectomy in the past. We wish to evaluate these to see the long term effects of central compensation, e.g. is nystagmus ever present to the unoperated side? How strong is directional preponderance as studied by hot and cold test limited to the remaining ear? Project 4). We wish to continue to examine the movements of animals (monkeys) who have had isolated lesions in the brain (mostly cerebellum); so far these findings have fitted in with clinical findings so that several eye movement syndromes are becoming apparent.